Ros,
I tend to leave my elevation of the Texture bed set at 0" that way it is set right ontop of the model. I dont believe the "the send to surface" command works for site modifiers. To get it to color and texture correctly make sure you type in the class layer in the object info. This can be confusing because you can select the class from the basic drop down but the wont change it correctly. You will need to type in it just below the box that states "Apply to"
Hope that helps,